Rectifier



Aug., l1, 1931.v F. J. msm-IER RECTIFIER Filed Jan. 18, l1929 Alfy.

Patented Aug. 11, 1931 UNITED STATES PATENT OFFICE FRANZ JOSEPH FISCHER, OF DRESDEN, GERMANY, ASSIG-NOR TO THE FIRM KOCH & STERZEL AKTIENGESELLSCHAFT, OF DRESDEN, GERMANY RECTIFIER Application filed January 18, 1929, Serial No. 333,287, and in Germany January 21, 1928.

My invention relates to rectiliers, more especially lof the synchronously rotating type. It has been suggested to connect the source of polyphase voltage to the rotary contacts of the rectiiier and to connect the poles of the voltage supply during the time in which they are cut `off from the twin circuit, to the nentral point of the source ot voltage by means of auxiliary resistances, the magnitude of '10 which is of the order of the impedance of the load circuit. In such arrangements compensating currents are produced when the rotary contacts leave one of the poles and reach another pole. It is an object ot my invention to 15 damp the compensating currents, so as to obtain steady operation of the rectifier. To this end I provide a single system of rotary contacts with two sets of staggered segments, one set serving ior receiving the direct current, while the segments in the other set are connected with each other across auxiliary resistances.

In polyphase current rectiiers of the kind described for high or low voltage it has already been proposed to connect the secondary polyphasefvoltage to the rotary contacts and to connect the poles of the polyphase current generator which are temporarily disconnected from the twin-conductor circuit, to the central or neutral phase points of the multiphase current generator across a resistance which is selected in proportion to the apparent load resistance. In this arrangement, however, the above-mentioned compensating currents are not damped in such manner as to obtain steady operation of the rectiiier. Besides rectiliers of this type involve the drawback that the rotary contacts are arranged on the shaft of the rectifier in several 1o sets side by side, thus increasing the length of the machine and requiring bearings of parv ticular design.

This drawback is eliminated according to this invention by providing a singlesystem of rotary contacts and two sets oit' staggered stationary segments one of which serves for taking the direct current, while the segments or the other row are interconnected across auxiiiary resistances. The length of the machine and the initial cost of the plant are thus greatly reduced and so are the compensating currents between the end of one and the beginning of the subsequent phase. This is due to the auxiliary resistances and cannot be obtained to a sutlicient extent by providing a single resistance. To provide such a connection in rectiliers as hitherto designed'would involve a very complicated system of connections as additional contact pieces with a corresponding number of brushes would have been required.

Another advantage may be obtained by connecting in a well known manner the comlnon connecting point of the auxiliary resistances with the neutral point of the source of alternating current, whereby the excessr nections are illustrated diagrammatically by .way of example.

In the drawings Fig. l is a perspective illustration of the rectilier, while Fig, 2 is a diagram of connections.

Referring to the drawings and iirst to F ig. 1,32 is a synchronous motor, the ystator of which is adapted to be adjusted by a handwheel 33 as is known in this art. l5, 16, and 17 are rotary contactson the shaft of the motor 32 which are pitched at 120 degs., their ends being connected with slip rings 12, 13, and 14, which are secured to the end wall of an insulating cylinder 34: in which they con-v tacts 15, 1G, 17 are rotating. 1825 are two rows (o and b) of segments arranged on the inner wall of the cylinder 31- in staggered relation and which are alternately connected with each other by the rotary contacts.

The segments 15S-Q1 serve for receiving the direct current by means of conductors 26, Q7, while the segments 22-25 are connected with each other across the auxiliary resistances 2S, 29, 30, and 31, and connected with the Zeropoint ofthe transformer 11 shown in 2,' the secondary polyphase voltage of which is led to the rotary contacts 15, 16, 17 across slip rings 12,13, and 14.

The operation of the rectifier is as follows: The rotary contacts 15, 1G, 17, being in the position shown in Figs. 1 and 2, the slipj ringz;

12 and the pole of the transformer connected to it vare, connected to the contact seg-f ment 18 and to the direct current line 26. The transformer pole connected to the slip ring 13 has been connected a momentI before to the contact segment 19 and to the direct current line 27. In the position shown in the drawings the rotary contact 1G is leaving the contacting segment` 19 and making contact with the segment 24. In consequence thereof the transformer Winding connected to the slip ring 13 is sliort-ciicuited over the resistance 30 so that the compensating current produced by the interruption of the contact between the rotary' contactl and the'contactingscgment 19 is damped by the resistance 30. The transformer winding connected to the slip ring 14 has been shortcircnited a moment before by the resistance 31. In the position shown in the drawings the rotary contact 17 is leaving the-contacting segment 25 connected to the resistance 31 and making contact with the contacting segment 21, thereby connecting the slip ring 1st to the direct current line 27.' The contacting segments are arranged in such manner that each of the rotary contacts 15, 1G, 17 is always in contact with atleast one ofthe contacting segments so that each slip ring and the transformer winding connected thereto are connected either to the direct current line or to one of the damping Aresistances 2S- 31. In consequence thereof compensating currents of undesirable intensity are not produced in the transformer windings and sparking ofth'e rectifying device is prevented.

I wish it to be understood that I do not desire to be limited to the exactl details of construction shown and described forobvions modifications will occnrto a person skilled in the art.

I claim z 1. Iiectifying device comprising a. plurality of Aslip rings, a source of'polyphase voltage connected to said slipl rings, contacting segments arranged in two .rows in staggeredrelation, resistances connected to one row of said contacting segments and to said source of voltage, connections connecting each contacting segment ofthe second row with the next but one segment, direct current terminals connected to said second row of contacting segments, and a rotary contact in Contact with each slip ring and adapted to slide successively along said contacting segments.

2. Recifying device comprising a plurality of slip rings, a source of polyphase voltage having a zero point and connected to said slip rings, contacting segments arranged in two rows in staggered relation, star-connected resistances connected to one row of said contacting segments and to the zero point of said source of voltage, connections connecting each contacting segment of the second row ywith .the next butuone segment, direct current terminals connected to said second row of contacting segments, and a-rotary contact in contact with eachslipring and adapted to slide sucessively alongsaid contacting segments.

3. Rectifying device comprising Aa'plurality of slip rings, a source of polyphase voltage having a zero point and connected to said slip rings, contacting segments arranged in two 4rows in staggered relation, star-connected resistances connected to one row of said contacting segments and to the zero point of said source of voltage so that only asingle resistance is inserted between each segment and the zero point of said source of voltage, connections connecting each contacting segmenty of the second row with the next but one segment, direct current terminals connected to said second row of contacting segments, and a rotary contact in contact with each slip ring and adapted to slide successively along said contacting segments.

et. Reetifying device comprising' an insulating cylinder, an end wall insaid cylinder, a plurality of slip rings supported by said end wall, a source of polyphase voltagef connected to said slip rings, an inner wall in said cylinder, contacting segments arranged onsa-id inner wall in two rows in staggered relation, resistances connected to one row of contacting segments and to said'source of" voltage, connections connecting each contacting segment of the second row ith the next bntone segment, direct current terminals connectedto said second row of contacting segments, and a rotary contact in contact with` each slip ring and adapted to slide successively along said contacting segments, said Vrotary contacts being arranged within said cylinder.

5. Rectifying devicecomprising a rotatably supported insulating cylinder, an end wall in said cylinder, a plurality ofslip rings supported by said end wall, al source of polyphase voltage connected to said' slip rings, an inner Wallin said cylinder, contacting segments arranged on said inner wall in two rows in staggered relation, resistanoes connected to one row of said contacting segments and to said source of voltage, connections connecting each contacting segment of the second row with the next but one segment, direct current terminals connected to said second row of contacting segments, and a rotary Contact in Contact with each slip ring, and adapted to slide successively along said contacting segments, said rotary contacts being arranged within said cylinder.

In testimony whereof I affix my signature.

FRANZ JOSEPH FISCHER. 

